Data Defining the Role of CCR9 and its Chemokine Ligand (TECK) in Colonic Disease were also Presented

Mountain View, CA.,  October 27, 2010  -- ChemoCentryx, Inc., today announced that it reported one-year results from the Company's PROTECT-1 Study (the Prospective Randomized Oral Therapy Evaluation in Crohn's disease Trial) of Traficet-EN (CCX282-B) in patients with moderate-to-severe Crohn's disease. Traficet-EN, an orally bioavailable CCR9-specific chemokine receptor antagonist showed clinical efficacy in a 12-week Induction period, as well as a 36-week Maintenance period. Specifically, Traficet-EN demonstrated evidence of clinical efficacy in the reduction of disease activity as defined by a 70-point or 100-point decrease in the Crohn's Disease Activity Index (CDAI) during the Induction period. Furthermore, approximately 50% of patients receiving Traficet-EN in the Maintenance period were in clinical remission (CDAI less than 150) by the end of the 36 weeks compared to 31% of patients receiving placebo. Traficet-EN continued to be safe and well tolerated. Phase III clinical trials designed to evaluate Traficet-EN in patients with moderate-to-severe Crohn's disease are expected to initiate before the end of the year.

Additionally, conclusive evidence was provided that the involvement of the CCR9 and its chemokine ligand (TECK) in inflammatory bowel disease (IBD) is not just restricted to the small bowel, but is relevant to inflammation of the large bowel as well. These findings as well as the Traficet-EN one-year study results were highlighted at the 18th United European Gastroenterology Federation (UEGW) meeting in Barcelona, Spain in a poster presentation entitled "One-Year Results from PROTECT-1 Study of Intestine-Specific Chemokine Receptor Antagonist CCX282-B (Traficet-EN) in Crohn's Disease" and in an oral presentation entitled "CCR9 Inhibition in the Treatment of Colonic Inflammation" presented by Dr. Juan C. Jaen, Senior Vice President, Drug Discovery and Chief Scientific Officer, ChemoCentryx, Inc.

"The PROTECT-1 study data provide a powerful validation for targeting the chemokine system to treat inflammatory diseases," stated Thomas J. Schall, Ph.D., President and Chief Executive Officer, ChemoCentryx. "Maintaining remission in patients with a complicated disease such as Crohn's through this novel mode of action is nothing short of groundbreaking. Complementing the success of this trial is the fact that our scientists have for the first time definitively identified CCR9 and its chemokine ligand in the large bowel which will no doubt expand the number of digestive disorders that Traficet-EN could potentially treat. We are proud of these accomplishments which further validate the strength of our technology as we continue to advance novel chemokine-based medicines through the clinic to treat inflammatory and autoimmune diseases."

PROTECT-1 Study Results
At week 52, 47% of subjects on Traficet-EN were in remission compared to 31% on placebo (p=0.012) with 41% of subjects on Traficet-EN in corticosteroid-free remission vs. 28% on placebo (p=0.04). At the end of the 12-week Induction period, CDAI 70 response rates were 47% on placebo, 56% on Traficet-EN 250 mg qd, 61% on 500 mg qd (p=0.039 vs. placebo) and 49% on 250 mg bid. After additional treatment with Traficet-EN 250 mg bid between weeks 12 and 16, subjects demonstrating a CDAI 70 response were re-randomized to placebo or Traficet-EN at 250 mg bid from weeks 16 to 52. During this time, median CDAI continued to decrease from 128 to 95 in the Traficet-EN treatment group and increased from 136 to 146 in the placebo group, resulting in a difference between groups of 51 points by week 52. Traficet-EN continued to be safe and well-tolerated after extended use.

About Traficet-EN (CCX282-B)
CCX282-B is a small molecule, orally bioavailable drug that is administered in capsule form and which is believed to modify the inappropriate immune system response underlying inflammatory bowel disease (IBD) by blocking the CCR9 chemokine receptor. In adults, CCR9 is a highly specific receptor expressed by inflammatory T cells that migrate to the digestive tract. The migration of inflammatory cells to the small and large intestine is believed to cause the persistent inflammation seen in Crohn's disease and ulcerative colitis -- the two principal forms of IBD. In addition to the PROTECT-1 study, ChemoCentryx has completed six Phase I clinical trials and one four-week Phase II Crohn's disease trial of CCX282-B at doses up to 1000 mg twice daily, demonstrating that the drug candidate is well-tolerated and appropriate for once-daily or twice-daily oral dosing. CCX282-B may offer advantages over existing therapeutic approaches for Crohn's disease by potentially offering reduced side effects and convenient oral dosing to patients. In January 2010, GlaxoSmithKline (GSK) exercised an option to obtain an exclusive worldwide license for the further development and commercialization of Traficet-EN (GSK 1605786).

About Crohn's Disease
Crohn's disease is a chronic inflammatory condition of the gastrointestinal tract. It is estimated that the disease affects over 500,000 patients in Europe and North America. Patients suffer periods of flare-ups characterized by intense symptoms, interspersed with periods of relative remission where symptoms decrease or disappear. As Crohn's disease is a chronic condition, patients continue on therapy from the time of diagnosis over the course of a lifetime, layering additional therapies as flare-ups recur or persist in an effort to reduce symptoms. When medications can no longer control symptoms, patients have few options beyond surgery.

About ChemoCentryx
ChemoCentryx, Inc., is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing orally-administered therapeutics that target the chemokine and chemoattractant systems in order to treat autoimmune diseases, inflammatory disorders and cancer. The chemokine system is a biological network that regulates inflammation via a collection of secreted chemokine molecules, or ligands, and their specific cell surface receptors. Based on its proprietary drug discovery and drug development platform, ChemoCentryx has internally generated multiple clinical and preclinical-stage programs, each targeting distinct chemokine and chemoattractant receptors with different small molecule compounds. ChemoCentryx's lead compound, Traficet-EN, a specific CCR9 antagonist, completed a Phase II/III multi-national clinical trial, called PROTECT-1, in patients with moderate-to-severe Crohn's disease, where it demonstrated the ability to induce a clinical response and to maintain clinical remission over the course of the trial. In addition, CCX025, also a CCR9 antagonist, has successfully completed a Phase I clinical program. Other clinical programs include CCX140, which targets the CCR2 receptor, in Phase II clinical development for the treatment of type 2 diabetes mellitus; CCX354, a CCR1 antagonist in a Phase II clinical trial for the treatment of rheumatoid arthritis; and CCX168, a C5aR antagonist, in Phase I clinical development. ChemoCentryx also has several programs in preclinical development. ChemoCentryx is privately held. For more information, please refer to www.chemocentryx.com.

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